Functional agglomerated speckles, method for manufacture thereof and dentifrices containing such speckles

ABSTRACT

Functional agglomerated speckles, for incorporation in dentifrices, include agglomerates of a water insoluble powdered functional material and water insoluble, ethanol soluble ethyl cellulose. Such speckles satisfactorily maintain their integrity and identity during processing of the dentifrice after addition of the speckles to the main dentifrice body but on storage, after packaging of the dentifrice in dispensing tubes, soften sufficiently so as to become essentially impalpable to one utilizing the dentifrice in brushing his teeth. Despite such softening the speckles continue to maintain their identity as speckles in the dentifrice. The speckles are especially useful in translucent or transparent gel dentifrices which contain components, such as flavoring and surface active agents, which may controllably soften the speckles on storage. Also described in the specification are methods for the manufacture of the mentioned speckles, dentifrices incorporating them, methods for manufacturing such dentifrices and such dentifrices packaged in end use dispensing containers.

This invention relates to functional agglomerated speckles forincorporation in dentrifices. More particularly, it relates to suchspeckles and to dentifrices containing them, wherein the speckles aremade from a water insoluble powdered functional material, such as adental polishing agent, and water insoluble, ethanol soluble ethylcellulose. The invention also relates to methods for manufacturing suchspeckles and such dentifrices and to such dentifrices packaged indispensing containers, such as transparent or translucent containersthrough which the speckles in a transparent or translucent geldentifrice may be viewed. To obtain desired visual effects the speckleswill usually be of a color which contrasts with the rest of thedentifrice.

Prior art toothpastes and gels which incorporated contrastingly coloredspeckles are known. Although such speckles in some cases are primarilyfor aesthetic effects, they may be based on functional components, suchas polishing agents, and they can perform desired functions in thedentifrice, in addition to making it of attractive appearance. Variouscolors and combinations thereof in the speckles may serve to identifythe particular type of dentifrice, such as fluoride and non-fluoridedentifrices. Incorporation of materials in the speckles may help toprevent reaction or premature reaction with other dentifrice components.When the speckles comprise mostly water insoluble material, such as apolishing agent, they can be present in a transparent or translucent geldentifrice without objectionably clouding the gel. Thus, the gel remainsclear, with the speckles being visible therein, and the speckles providea decorative and aethestically improved appearance for the product.

In the past various speckled dentifrices have included speckles whichwere initially palpable but became impalpable during toothbrushing.Although such products have met with technical approval it has also beenfound desirable to market another type of speckled dentifrice, like thatof this invention, in which the speckles, although readily visible anddiscrete, are impalpable initially and subsequently during brushing ofthe teeth.

Among the various prior art references showing dentifrices incorporatingspeckles and other dispersed solids therein, the closest to the presentinvention that are known to applicants are U.S. Pat. Nos. Re. 29,634;3,929,988; 4,003,971; 4,089,943; and 4,220,552. The reissue patentdescribes a dentifrice containing visible and palpable, substantiallywater-insoluble, agglomerated particles of polishing agents. Bindingagents are employed in the manufacture of the described speckles andamong the water soluble binders methyl cellulose is mentioned. However,methyl cellulose is water soluble and therefore does not provide aspeckle which maintains integrity during lengthy processing andeventually softens to an impalpable unit on storage in a dentifrice.U.S. Pat. No. 3,929,988 relates to a dentifrice containing encapsulatedsweetener. Ethyl cellulose is mentioned among various other materialsuseful for coating the sweetener to make the capsules or spheres, whichmay be visible or "micro-size", and are dispersed in the dentifrice.U.S. Pat. No. 4,003,971 teaches making dentifrice speckles and describesthe advantages of water-insoluble binders for such speckles. The patentmentions the use of gums as water insoluble binders but does notdisclose or suggest ethyl cellulose. U.S. Pat. No. 4,089,943 teachestoothpaste formulations having dispersed therein visible agglomeratedparticles of dental polishing agent. The advantages of both watersoluble and water insoluble agglomerating or binding agents arementioned in the patent but ethyl cellulose is not suggested for use asa binder. Finally, U.S. Pat. No. 4,220,552 teaches microencapsulation ofsodium fluoride by lower alkyl cellulose, such as ethyl cellulose, anddispersing of the capsules in a dentifrice. The patent does not relateto agglomerates and the employment of ethyl cellulose as anencapsulating agent does not make obvious its use as an agglomeratingagent useful in making the present speckles.

The present invention is one wherein ethyl cellulose, which is waterinsoluble but ethanol soluble, is utilized as an agglomerating agent fora functional water insoluble powdered material made into dentifricespeckles of improved properties. Prior speckles, made with water solublebinders, such as methyl cellulose, could disintegrate during processingafter mixing in with other dentifrice components, such as those inpreviously formulated gel or paste media, if the speckled dentifrice washeld too long in the processing equipment, which can happen, as whenmechanical breakdowns of processing equipment occur. Such losses ofintegrity of the speckles could take place because such dentifricescontain water, which can solubilize the water soluble binders of thespeckles and lead to separation of the component particles of thespeckles. The dissolving of the binder can be minimized in such cases byprompt processing but when filling line holdups cause processing timesto be increased losses of product could result. Dentifrice speckles madewith ordinary water insoluble binding agents, as disclosed in the art(such art does not disclose ethyl cellulose), when dispersed indentifrice gels or pastes, tend to be palpable, and although that mayoften be desirable, in some dentifrices, e.g., those intended for use bypersons with sensitive gingiva, it is not. The ethyl cellulose employedas a binder for functional speckles in accordance with the presentinvention satisfactorily maintains the integrity of the speckles inaqueous dentifrice media for a sufficiently long time to allowprocessing after incorporation of the speckles in the dentifrice. Yet,apparently because of the presence of components of the dentifrice whichtend to soften the speckles on storage, such as flavoring agents, and insome cases, surface active agents, the speckles in the dentifrice aresoftened sufficiently during storage so that, although they maintaintheir integrity and independence and their distinctly separateappearances until they are used, they are impalpable and are readilydisintegrated during toothbrushing.

In accordance with the present invention functional agglomeratedspeckles, for incorporation in dentifrices, comprise agglomerates of awater insoluble powdered functional material and water insoluble,ethanol soluble ethyl cellulose. Preferably, the functional material isa dental polishing agent and comprises 75 to 98% of the speckles, withthe ethyl cellulose comprising 2 to 20% thereof and with the productoptionally including a coloring agent which may be 0 to 5% thereof, morepreferably 0.05 to 1%, when present. Also claimed in this applicationare a dentifrice containing such speckles, methods for the manufactureof the speckles and of the dentifrice, and a packaged gel dentifricecontaining the invented speckles dispersed therein.

The invention will be readily understood from the present specification,including the detailed description therein. However, in accordance withthe Statute and Rules of Practice a drawing of a packaged dentifrice ofthis invention is also provided and the FIGURE thereof will bedescribed.

The functional agglomerated speckles are comprised of two essentialcomponents, a water insoluble powdered functional material and a waterinsoluble, ethanol soluble ethyl cellulose. The first may becharacterized as the functional bodying agent and the second as thebinder. Various functional materials, all of which are preferably waterinsoluble, or at least, slowly soluble, can be employed, includingcolorants, such as pigments, germicides, ion exchange agents, polymericmaterials (which may contain other active components, sometimes watersoluble materials), and flavorings, but it is highly preferred that thefunctional base material for the speckles be a polishing agent orinclude a major proportion thereof. Of the polishing agents, normallyutilized in dry powder form to make the agglomerated speckles, thosepreferred are dicalcium phosphate, tricalcium phosphate, insolublesodium metaphosphate, alumina, silica, magnesium carbonate, calciumcarbonate, calcium pyrophosphate, bentonite and zirconium silicate, andsuitable mixtures thereof. Both anhydrous or calcined forms of thesematerials, such as calcined alumina, and hydrated forms, such asdicalcium phosphate dihydrate, may be employed but the anhydrous orcalcined materials are often preferred. Because the agglomerates willnormally desirably be opaque there is no need to match refractiveindices with those of the dentifrice vehicles (including othercomponents, too) but "transparent" polishing agents, with such amatching refractive index, e.g., 1.44 to 1.47, may be used to maketransparent or translucent speckles, as well as being used in making aclear gel dentifrice body containing polishing agent. Such "transparent"polishing agents include colloidal silicas and those sold under the markSyloid, as Syloids 63, 65, 72 and 74, under the mark Santocel, asSantocel 100 and as Zeo's 49, 113 and 119, and Zeodent. Also, syntheticalkali metal aluminosilicate complexes may be particularly useful,because they have refractive indices close to those of dental vehiclesincluding water, glycerol, sorbitol and gelling agent, which are thosenormally employed in the manufacture of dentifrices.

The water insoluble, powdered functional material utilized to make thepresent speckles will normally be of initial particle sizes in the rangeof 0.5 to 20 microns, preferably being within the range of 1 to 10microns, and more preferably of 2 to 8 microns. However, in someinstances larger particle sizes may be employed, as when theagglomerating operation tends to size-reduce some of the powder, as mayhappen in mixing before actual agglomeration begins.

The binding agent for the present speckles is ethyl cellulose. Thiseffective binder is water insoluble but is soluble in ethanol, and isgradually soluble in an aqueous glycerol-sorbitol medium which alsocontains "solvents" for it, such as flavorings and surfactants, whichare usually present in the dentifrices of this invention. Such ethylcellulose will usually have an ethoxy content in the range of about 45to 50%, preferably 48 to 50% or 48 to 49.5%. In a preferred ethylcellulose, such as that marketed by The Dow Chemical Company under thetrade name Ethocel Standard 10 Premium Ethyl Cellulose, the ethoxylcontent is in the range of 48.0 to 49.5%; the viscosity is 9 to 11centipoises; the moisture content is 2% maximum; chloride, as NaCl is0.15% maximum and ash content is 0.15% maximum. The test methodsemployed for the foregoing analyses are those incorporated in Test D914of the American Society For Testing Materials (ASTM). Because the ethylcellulose is intended for oral use the maximum content of arsenic, asAs₂ O₃, is three parts per million (p.p.m.), that of lead is 10 p.p.m.and that of heavy metals is 40 p.p.m., all by Food Chemicals Codex (FCC)testing.

In the 18-page Dow Chemical Company booklet entitled ETHOCELEthylcellulose Resins-Tough, Rugged Coatings, Adhesives, Hot Melts,copyrighted 1974, 1975 and 1978, hereby incorporated by reference,suitable ethyl cellulose resins for use as binders for the presentspeckles are described. Ethyl cellulose is supplied commercially as awhite to light tan granular powder of a degree of etherification suchthat there are 2.25 to 2.58 ethoxy groups per anhydroglucose unit, whichcorresponds to 45.0 to 49.5% ethoxy content (by weight). Of two gradesof ethyl cellulose commercially available the "standard" materials,which are preferred for the practice of the present invention, haveethoxy contents in the range of 48.0 to 49.5% (by weight), and the lesspreferred "medium" materials have ethoxy contents in the 45.0 to 46.5%range. Of course, such products are available in different viscosityranges, usually from 3 to 110 centipoises, with the medium materialtending to be more viscous.

The standard grade of ethyl cellulose tends to be soluble in aromatichydrocarbons, hydroaromatic hydrocarbons, chlorinated aliphatichydrocarbons and naval stores. It is also soluble in monohydricaliphatic alcohols, such as ethanol; monohydric cyclic alcohols, such asbenzyl alcohol phenylethyl alcohol and pine oil; ether alcohols, such asglycol ethers; ethers, such as diethyl cellosolve; esters, especiallyacetates, such as isopropyl acetate and sec-amyl acetate and esters ofhydroxy acids, such as methyl salicylate; and ketones, such ascyclohexanone and acetophenone. Generally, the medium ethoxy grade ofethyl cellulose is less soluble than the standard grade and so may bemore suited for use when greater proportions of solubilizing materialsare present in the dentifrice formula.

Among other physical properties of ethyl celluloses are: a specificgravity of about 1.1; water absorption after twenty-four hours immersionof about 1%; an impact strength, expressed as energy to break, of about1 to 12 ft. lbs./sq. in. of notch; a tensile strength of about 6,000 to9,000 lbs./sq. in.; an elongation of about 10 to 40%; a Rockwellhardness of about 70 to 110; a compression molding temperature of about320° to 350° F., a compression molding pressure of about 300 to 6,000lbs./sq. in.; and a specific heat of about 0.3 to 0.46. Ethyl celluloseis heat stable, light stable, colorless, odorless and tasteless.

Although it might have been expected that the best speckles would bemade from the least soluble binder material, it has been found thatethyl cellulose, as described in this invention, makes speckles of idealproperties, which maintain their individuality and integrity while beingprocessed and during storage, but which are also essentially impalpableduring use of the dentifrice in brushing. If desired, the character ofthe speckles may be changed, as by modifying the degree of ethoxycontent of the ethyl cellulose and/or by blending with it othersubstantially water insoluble binders of known types, some of which arementioned in the patents previously referred to, the disclosures ofwhich are incorporated herein by reference. The properties of thespeckles may also be regulated by adjusting the proportions offunctional material and the binder, as will be referred to subsequently.Thus, agglomerates may be made which will be stable during processingafter mixing, such as deaerating and filling, yet which will break uprapidly after the dental cream is extruded from its container or, ifdesired, such breaking up may be retarded so that the agglomerates willfeel harder and somewhat firmer to the user during brushing of histeeth. Of course, it is normally highly preferable for the speckles tobe essentially impalpable on use, while still maintaining their identityin the dentifrice.

The binder will normally be of particle size like that of the functionalpowdered material of the speckles, especially if the agglomerates are tobe made, at least in part, by compacting of powdered materials. However,because normally the speckles will be made by utilizing an alcoholicsolution of the ethyl cellulose, the particle sizes thereof are ofrelatively little importance.

The speckles, while sometimes white or colorless and possibly eventranslucent or transparent, or approaching such appearances, may also becolored, normally due to containing a suitable proportion of dye orpigment or a mixture of dyes and/or pigments. Any non-toxic dye orpigment of a suitable color, usually a strong color, such as one of asuitable hue, with a Munsell chroma greater than 4 and a Munsell valuein the 4 to 7 range, may be utilized, and in some instances weak colorsor pastels may be satisfactory or desirable. It is usually best toemploy a dye or pigment which is approved for drug and cosmetic use(D&C) or for food, drug and cosmetic use (FD&C). Representative ofsuitable dyes are D&C Reds Nos. 2, 3, 6, 7, 8, 9, 10, 11, 12, 13, 19,30, 31, 36 and 37; D&C Blue No. 1; FD&C Blues Nos. 1 and 2; FD&C RedsNos. 1, 2 and 3; FD&C Yellow No. 5; cosmetic green oxide; and cosmeticred oxide. Pigments of the foregoing dyes, known as lakes, are alsosuitable for use in coloring the speckles but normally the dyes will bepreferred. The mentioned pigments are often composed of dyes supportedon a finely powdered insoluble carrier and the pigments are dispersedrather than dissolved in the medium to be colored. The particle sizes ofpigments employed may be within the range previously given for thepolishing agents or may be sized like the binder. Sizes may be finer,e.g., in the 0.01 to 1 micron range. Particle sizes of dyes may besimilar but because they are normally employed in dissolved state, inwater or solvent, preferably being oil soluble and being dissolved inthe appropriate solvent, sizes are not important as long as the powderor particles are small enough so as to make the dye readily soluble inthe solvent chosen.

The speckles of this invention may be made by any suitable method,either wet or dry processes. Employing a wet granulation process, theethyl cellulose, in dry powder form, is first preferably blended withpolishing agent and dye or pigment, if present, and ethanol. Waterand/or lipophilic solvent may be present with the ethanol and a dye orpigment for coloring the speckles may also be present. Alternatively,and often preferably, an ethanol solution of ethyl cellulose may have asuitable dye or pigment and the polishing agent admixed with it. Theproportions of components will be such as to result in speckles of thedesired composition and the proportion of solvent(s) will normally befrom 5 to 50% of the mix, preferably 5 to 25% thereof. The production ofthe dispersion may be by means of a Hobart mixer, Dravo pan, or othersuitable mixing device or granulator for wetting powder(s), and theorder of addition of the various components of the dispersion may beadjusted as best befits the mixing or blending apparatus employed. Apreferred way of producing the speckles is by forcing the "wetted" mixof polishing agent and ethyl cellulose (with dye or pigment, if used)through a screen having uniform openings, which usually will be in therange of about 150 to 2,000 microns (about in the No. 10 to 100 sieverange, U.S. Sieve Series) and the "extruded" agglomerates are thendried, usually either in air or in an oven. Instead of screens othermeans, such as pressure extruders, may be employed for extruding orotherwise pelletizing the mix, after which the particles resulting aredried. The particles are then classified into desired size ranges,normally in the Nos. 10 to 80 range, preferably Nos. 40 to 80 and morepreferably Nos. 30 to 60 (U.S. Sieve Series). Of course, if the wet massis formed in a Dravo pan the forced screening or other extruding may beomitted. Generally, when the particle sizes are larger than 2,000microns (No. 10 sieve) they will be less satisfactory for introductioninto the oral cavity of a user and when less than about 177 microns indiameter (No. 80 sieve) they will not be as readily apparent and hence,will not be of as attractive an appearance.

Instead of employing the wet granulation process a dry or sluggingprocess may be utilized, wherein the components of the speckles may bepressed to large tablet size and such tablet may then be broken up, withparticles thereof in the desired size range being separated from theothers. In such tableting process it may be desirable to employ a waterinsoluble lubricant, such as talc, magnesium stearate, calcium stearateor stearic acid, which also helps to facilitate agglomeration.Similarly, such materials and other water insoluble adjuvants may bepresent when wet granulation methods are used. The speckles made arepreferably dry, containing no moisture, but moisture contents of up to10%, e.g., 1 to 5%, may be present without causing any serious adverseeffects on the properties of the speckles.

The proportions in the speckles of water insoluble powdered functionalmaterial, such as dental polishing agent, and ethyl cellulose, will besuch that the ethyl cellulose will be the minor component of thespeckles and the powdered functional material will be the majorcomponent thereof (although allowance should be made for the presence ofother materials too, such as colors and adjuvants). Generally, thedental polishing agent or functional material is from 75 or 80 to 98% ofthe speckles, preferably 85 to 97% thereof, the ethyl cellulose will be2 to 20% of the speckles, preferably 3 to 15% thereof and the colorantwill be 0 to 5% of the speckles, such as about 0.05 to 1% thereof, allon a dry basis, free of water and ethanol or other solvent.

The dentifrice in which the speckles are distributed may be any suitablesuch product, because in the present invention it acts primarily as themedium for the speckles, maintaining them independent, individual andseparate, while performing its normal dentifrice functions. Opaquedentifrices are useful media for the present speckles but it is highlypreferred that the dentifrice be transparent or translucent and normallybe of a type characterized as a gel. Dentifrices normally comprisewater, humectant, gelling agent, dental detergent and a dental polishingagent, usually with flavoring and/or coloring too. Among variousfunctional adjuvants are fluorides, stabilizers, anti-caries agents andantibacterial compounds.

The water employed will preferably be deionized water, although citywaters, both soft and hard, may also be utilized. The gelling agent isnormally a water soluble natural or synthetic gum or gum-like material,among which are carrageenan, gum tragacanth, xanthan gum, alginates,alkali metal carboxymethyl cellulose (preferably sodium carboxymethylcellulose), hydroxymethyl carboxyethyl cellulose, polyvinyl pyrrolidone,starch, and hydrophilic colloidal carboxyvinyl polymers, such as thosesold under the trademarks Carbopol 934 and 940. Although various polyolsmay be utilized as humectants those preferred are of 3 to 6 carbon atomsand 3 to 6 hydroxyls per molecule, and those of choice are glycerol andsorbitol. The glycerol is in normal liquid state, generally being about99% or more pure, and sorbitol, normally being a solid, is frequentlyutilized as a 70% aqueous solution thereof (70% sorbitol, 30% water).The three mentioned components may be considered as the mainconstituents of the dentifrice vehicle, in which flavor and detergentmay also be incorporated. Such detergent may include a soap but normallywill be a non-soap synthetic organic surface active agent havingdetersive properties. Preferably such detergent will be of the anionictype, although nonionic detergents are also useful, ampholyticdetergents can be employed, and cationic detergents can be acceptableunder some circumstances.

The preferred anionic detergents are especially useful because theycombine excellent cleaning action and foaming properties. Normally, suchcompounds include hydrophilically and lipophilically balanced moieties,with the lipophilic moiety usually being a higher fatty alkyl or acyl of10 to 18 carbon atoms, preferably 12 to 16 carbon atoms, and thehydrophile being alkali metal, e.g., sodium, potassium, or ammonium orlower alkanolammonium. Suitable such anionic detergents are: the watersoluble salts (normally alkali metal and preferably sodium or potassium)of higher fatty acid monoglyceride sulfates, such as the sodium salt ofthe monosulfated monoglyceride of hydrogenated coconut oil fatty acids;higher alkyl sulfates, such as sodium lauryl sulfate; alkylarylsulfonates, such as sodium linear dodecyl benzene sulfonate; higheralkyl sulfoacetates; higher fatty acid ester 1,2-dihydroxypropanesulfonates; the sodium salts of sulfated polyethoxylated alcohols; andthe substantially saturated higher aliphatic acylamides of loweraliphatic aminocarboxylic acid compounds, such as N-lauroyl sarcosine,and the sodium, potassium and ethanolamine salts of N-lauroyl-,N-myristoyl-, and N-palmitoyl sarcosine, all of which sarcosinecompounds are preferably substantially free from soap or similar higherfatty acid material. Among the nonionic detergents, ethoxylated sorbitanmonostearate, with approximately 20 mols of ethylene oxide per mol;condensates of ethylene oxide with propylene oxide and propylene glycol(Pluronics); polyethoxylated higher fatty alcohols, such as the Neodols(23-6.5 and 45-11, for example); and condensation products ofalpha-olefin oxides containing 10 to 20 carbon atoms, polyhydricalcohols containing 2 to 10 carbon atoms and 2 to 6 hydroxyl groups, andeither ethylene oxide or heteric mixtures of ethylene oxide andpropylene oxide, are useful. Quaternized imidazoyl derivatives, such asMiranol C₂ M, and other Miranols represent useful amphoteric detergentsand the quaternary ammonium halides, such as dimethyl dicetyl ammoniumbromide, represent cationic detergents.

The various polishing agents, which are dispersed in the dentifricevehicle (or vehicle plus detergent and any other adjuvants) are thosepreviously described for conversion to speckle form. Also useful in suchgroup of materials are synthetic finely divided silicas, such as thosesold under the trademarks Cab-O-Sil M-5, Syloid 244, Syloid 266, AerosilD-200, Zeosyl 200 and Zeothix 265, which are normally utilized for onlya small percentage of the polishing agent, normally being no more than 1to 9% by weight of the total dentifrice, and which are useful forthickening or gelling the vehicle and improving the clarity of thedentifrice.

The dentifrices of this invention will normally contain suitableflavoring and/or sweetening materials, Examples of flavors include theflavoring oils, such as those of spearmint, peppermint, wintergreen,sassafras, clove, sage, eucalyptus, cinnamon, lemon and orange, and thesweetening agents include sucrose, lactose, maltose and saccharin.Desirably for fluoride dentifrices there will also be present sodiumfluoride, stannous fluoride, potassium fluoride, potassium stannousfluoride, sodium hexafluorostannate, stannous chlorofluoride and/orsodium monofluorophosphate.

The flavoring materials include various well known essential oils,mainly terpenes; esters; alcohols, aldehydes, ketones, and otheraromatic substances, many of which emit aromatic odors and fragrances.Because flavor is a simultaneous physiological and psychologicalresponse obtained from the presence of a substance in the mouth anddepends on the senses of taste, smell and feel, with smell often beingof primary importance, it is not surprising that aromatic materials areimportant components of flavors. In the present instances advantage istaken of this fact and of the chemical natures of such materials which,as was previously indicated in the discussion of solubilities of ethylcellulose, permit the ethyl cellulose binder in the present speckles tobe slowly solubilized by the solubilizing substances in the flavoringmaterial, causing softening of the speckles but not causing theirdisintegration. For example the terpenes, which are hydrocarbons andwhich constitute an important class of perfumery or flavor materials,are good solvents for the ethyl cellulose of this invention, as are manyother flavoring materials, such as those previously named (as flavoringoils) above, and others well known to the perfumery and flavoring arts.By utilizing the flavoring essences in the dentifrice composition tosoften the ethyl cellulose speckles and thereby make them impalpable,which is an aim of this invention, it is unnecessary to add anothercomponent to the dentifrice or the speckles for this purpose. Also,because of the relatively small proportion of flavoring materialnormally present in a dentifrice, with the proportion of the lipophilicpart of the flavor often being lower, a desirable slow softening of thespeckle particles can result, usually due to a relatively low masstransfer rate for the "solvent" material, which transfer rate isespecially slowed due to the gelatinous nature of the dentifrice. Thus,even if some flavoring material at the interface with the specklestarted to soften the ethyl cellulose thereof while the dentifrice wasbeing blended, the flavor solution of ethyl cellulose would soon becomesaturated and this would inhibit further quick dissolving of the ethylcellulose. Still with the passage of the normal time a dentifrice spendsin storage before sale and use, which time will often be at least about2 weeks and sometimes more (with certain dentifrice formulas it isdesirable to allow them to age to improve flavor and productuniformity), the speckles become impalpable, yet remain distinct.

Although it is considered that the flavoring materials, particularly thelipophiles, which exert substantial solvent action on ethyl cellulose,are the most important slowly solubilizing components of the presentdentifrice, the surface active agent component, which includes alipophilic moiety, may also have an appreciable solubilizing effect andby means of its wetting action, may promote mass transfer in adentifrice tube and thereby increase the solubility rate of the ethylcellulose. It is also possible that combinations of other constituentsof the dentifrice, including some of the sweetening agents and vehiclecomponents, will further assist in solubilization of the ethyl celluloseto the extent desired, while not promoting premature softening of thespeckles.

Colorants, such as those previously mentioned with respect to thespeckles, may be employed, normally in lesser proportion, so as toprovide a base which contrasts with the speckles. Various other adjuvantmaterials may be present in the dentifrice, including preservatives,silicones, chlorophyll compounds and ammoniated materials. Normally,when a gel dentifrice is made which is intended to be transparent ortranslucent, the polishing agent chosen will be one having an index ofrefraction closely matching that of the rest of the dentifrice medium.Of course, in such clear gel formulations the amount present ofinsoluble materials which would cloud the gel will normally beminimized. When the pH of the dentifrice is adjusted, and the pH isdesirably within the range of 3 to 10, more desirably from 3.5 to 5 whenstannous ions are present and 4.5 to 7 in the absence of such ions,organic acids, such as citric, malonic, and fumaric acids, may beemployed.

In the dentifrice of this invention a dental polishing agent isuniformly distributed throughout the vehicle of water, humectant andgelling agent, with a dental detergent and the desired proportion offlavor already in it. Then the speckles, which also preferably contain apolishing agent (and often of a different type from that in the body ofthe dentifrice), are uniformly distributed throughout the dentifrice,usually comprising 0.1 to 10% of the dentifrice, preferably 0.5 to 5%thereof, more preferably 1 to 3% thereof and most preferably 1.5 to 2.5%thereof. The dental base will usually comprise: about 5 to 30% water,preferably 10 to 25% and more preferably 10 to 20%; about 20 to 70% ofhumectant, preferably polyol humectant, more preferably 45 to 65%thereof and most preferably 50 to 60% thereof; and about 0.1 to 5% ofgelling agent, preferably 0.1 to 1% and more preferably 0.2 to 0.5%thereof. The humectant is preferably a mixture of glycerol and sorbitolwherein the glycerol content is 5 to 40% of the dental base, preferably20 to 30%, and the sorbitol content is 5 to 50%, preferably 25 to 35%.The preferred gelling agent is sodium carboxymethyl cellulose, and apreferred proportion thereof utilized is about 0.3 to 0.4%. The dentaldetergent content will normally be from 0.5 to 5%, preferably 0.5 to 3%,and a preferred such detergent is sodium lauryl sulfate. The polishingagent in the dentifrice base, exclusive of that in the speckles, isnormally 10 to 40%, preferably 15 to 30% and most preferably 20 to 25%,including Syloid 244 type silicas, which are also employed forthickening. Various other materials, including flavors (usually 0.5 to2%), color, preservatives, sweeteners, and tooth hardeners (fluorides)will normally total no more than 10% of the dentifrice, preferably beingfrom 2 to 7% thereof. Utilizing the proportions of the variousconstituents within the ranges given, with respect to the speckles andthe medium in which they are distributed, results in an attractiveproduct which is stable during storage and in which the speckles areuniformly and attractively distributed.

To prepare the speckled dentifrice, after first producing the speckles,is comparatively simple but an important consideration is that minimalmechanical agitation should be employed so as to prevent or delay anydisintegration, softening and solubilization of the speckles in thedentifrice. It is considered that lipophilic materials and solventspresent, such as those in flavoring oils, will slowly solubilize ethylcellulose, but not to an objectionable extent in the absence of vigorousagitation in processing. If the dentifrice is at an elevated temperatureduring such mixing, possibly due to manufacturing limitations inprocessing, it is even more important to minimize agitation. However,with the ethyl cellulose binder of this invention employed in themanufacture of the speckles, manufacturing restrictions may be lessstringent, but care should still be exercised. Suitable equipments fordistributing the speckles throughout the dentifrice include Banbury ordough mixers operated at low speeds but other gently operated blendersmay also be used providing that mixing is controlled so as to preventsubstantial breakdowns, dissolvings or disintegrations of the speckles.Normally mixing blade speed will be on the order of one to five r.p.m.and mixing will last from one to five minutes. After completion of theblending the dentifrice is deaerated and filled into containers, such asresilient or collapsible tubes. If vacuum is employed during mixingoperations deaeration may be omitted.

The manufacturing method described in the preceding paragraph is astandard method for making speckled dentifrices, with the exception ofthe processing of the present speckles in such dentifrice and therequirement for the presence of slowly solubilizing lipophilic materialin the base of the dentifrice, together with the speckles bound togetherby ethyl cellulose. However, recently new methods have been invented forfacilitating blending of the speckles into the dental gel body withoutexcessive agitation. Such methods and the apparatuses by means of whichthey are practiced are the inventions of Edward J. Gibbons and John F.Smith, respectively, and are the subjects of patent applications to befiled by them on the same date as the present application. In suchmethods the dentifrice is fed through an orifice to form a falling,curving ribbon onto which speckles are uniformly dropped at a constantrate, after the speckled gel dentifrice is transported to fillingequipment by means of a positive displacement variable walled pump, suchas one of the Moyno type.

Although normal collapsible aluminum tubes with capped dispensingopenings, through which the dentifrice may be squeezed, are mostcommonly employed, it is often preferred to make the packaged dentifriceby utilizing a deformable tube of clear or translucent synthetic organicpolymeric material, such as polyvinyl chloride, polyethylene,polyvinylidene chloride or similar material through which the attractiveappearing speckled dentifrice may be viewed.

In FIG. 1 there is shown a plan view of the clear walled container 11,which is made of transparent polymeric material (PVC), including body13, shoulder 15, threaded neck 17 and cap 19, with the cap having beenremoved from the tube. As illustrated, some of the dentifrice 21 isbeing dispensed from tube 11 through neck 17 onto the bristles of atoothbrush 12. In the dentifrice there are clearly shown inventedspeckles 23 in the continuous dentifrice medium 25. It is noted thatsuch speckles are initially impalpable although they are easily visible.During toothbrushing they break down into smaller entities ofessentially the same sizes as the component polishing agent. Of course,the speckle polishing agent acts together with that in the dental gel tohelp clean and polish the teeth.

The following examples illustrate but do not limit the invention.Throughout the specification, including the working examples, and in theclaims, all parts are by weight, unless otherwise indicated.

EXAMPLE 1 (Actual)

Five parts of ethyl cellulose (10 centipoises), of the physicalcharacteristics described previously in the specification and in powderform, are dissolved in five parts of ethanol (95%) and are mixed in aHobart mixer with 95 parts of calcined alumina (Microgrit WCA 9F) ofparticle sizes in the range of 0.5 to 10 microns and an average particlesize in the range of 3 to 5 microns. Mixing is continued for about fourminutes until the blend is uniform, after which the mix is forcedthrough a No. 10 (U.S. Sieve Series) screen and the "extruded" materialis oven dried for one hour at 65° C. The dried agglomerates are thenscreened through a No. 30 screen and the cut that rests on a No. 60screen, the dried speckles comprising the calcined alumina and ethylcellulose, is collected. The speckles produced are of angular shapes,with the ratios of maximum length to maximum width usually being withinthe 1 to 2 range and most of the particles being of such a ratio withinthe 1.1 to 1.5 range. The angularity of the particles may be a factor inmaking the dentifrices so attractive in appearance, at least for someconsumers.

A transparent (or translucent) dentifrice base (all components exceptspeckles), is made of the following formula:

    ______________________________________                                        Component                Parts by Weight                                      ______________________________________                                        Glycerol (99.3% pure)    25.00                                                Sodium carboxymethyl cellulose                                                                         0.35                                                 Sorbitol (70% aqueous solution)                                                                        36.04                                                Polyethylene glycol 600  3.00                                                 Water                    3.00                                                 Sodium saccharin         0.25                                                 Sodium benzoate          0.50                                                 Blue dye (FD&C Blue No. 1, 1% aqueous                                         solution)                0.20                                                 Sodium monofluorophosphate (1 to 60 microns)                                                           0.76                                                 Silicon dioxide (Zeo 49) 18.00                                                Synthetic silica (Syloid 244)                                                                          5.50                                                 Sodium lauryl sulfate    1.20                                                 Flavor (spearmint, peppermint, wintergreen,                                   clove, etc., as desired) 1.20                                                                          95.00                                                ______________________________________                                    

Five parts of the described speckles, with particle sizes -30+60 (U.S.Sieve Series), are gently blended in a slow moving mixer (about twor.p.m.) with 95 parts of the described dentifrice base, after which themix is deaerated and automatically filled into capped collapsible tubeswhich are then sealed. During the mixing, dearation and tube fillingsteps the speckles, which are substantially evenly distributed throughthe dentifrice, remain discrete, independent and undissolved in thedentifrice base so that when the tube is opened, after filling, andpreferably, after storage for about a month, and the dentifrice issqueezed through the discharge opening thereof, the speckles appear tohave retained their initial integrity, contrasting with the bluish gel.When the product is evaluated immediately after filling, and withoutbeing stored, the speckles are palpable but, upon storage before use,for periods from two weeks to a year or more, are sufficiently softened,as by solubilization of the ethyl cellulose by the flavoring oil,sometimes with the aid of the dental detergent or other surface activeagent that may be present, and other components, so as to appeardistinct and not "smeared", but yet to be satisfactorily impalpable.During toothbrushing with the dentifrice the speckle particles arereadily reduced in size, are not irritating to the gingiva, and arereadily dischargeable from the oral cavity on completion of brushing.

Although the presence of the anionic detergent in the dental base may beof assistance, it is thought that the controlling component of such baseis the 1.2% of flavoring agent present. A proportion of such an agent ora mixture thereof from 0.5 to 2%, preferably 0.8 to 1.5%, of which atleast half is normally active as a solvent for ethyl cellulose, isdesirable for best speckle dispersions, and the flavor will usuallyinclude over 50% and often over 80% of solubilizing hydrocarbons,esters, alcohols and aldehydes.

The manufacturing method described for the dentifrice, in which thespeckles are dispersed in the body of the gel, is one in which themixing operation should be watched to make sure that the speckles arenot disintegrating and, at any sign of this happening mixing should behalted and, providing that the dentifrice appearance is notsignificantly adversely affected, usually by being made unacceptablycloudy, filling of the tubes should be undertaken promptly. Instead ofemploying the described mixing method it will often be preferable toutilize the Gibbons or Smith techniques, previously referred to herein,wherein a regulated even "fan" of speckles is deposited by means ofgravity on a continuously falling extruded ribbon of gel, to which thespeckles adhere, so as to obtain uniformity of distribution of thespeckles in the dentifrice. With respect to such process and apparatusthe specification and drawing of such patent application are herebyincluded by reference.

When the speckled dentifrice of this invention is packed in acollapsible aluminum tube the speckles in the dentifrice are not visibleuntil discharge from the tube but at that time they are maintaineddiscrete in the toothpaste extruded and impart to it an attractive anddistinctive appearance. However, when instead of the normal aluminumtubes one employs resilient transparent tubes, such as tubes ofpolyvinyl chloride or other suitable polymer, the speckles can be seenthrough the tubes and through the transparent gel dentifrice base, andtheir movements, on discharge, can be observed. This provides anadditional aesthetic benefit and helps to make toothbrushing moreinteresting, at least for children. Additionally, the functionalspeckles act as a reminder to the person using the dentrifice of thepresence of polishing agent or other functional constituent in thedentifrice and thereby help to remind him of the importance of brushingso that such component may be effective.

The formula given above is one for a gel dentifrice in which the normal41.04% of sorbitol solution had been reduced to 36.04% to allow for theintroduction of the 5% of speckles. The effect of this change in theformulation is to maintain the percentages of the other dentifricecomponents the same as in an unspeckled product, with the exception ofthe major component, the sorbitol solution. It is considered that withother variations in the contents of speckles in such dentrifrices suchprocedure for modifying the formula may continue to be followed.However, it is also feasible to start with the initial gel formulation,e.g., containing 41.04% of sorbitol solution, and reduce each of thecomponents proportionately to allow for the introduction of the desiredpercentage of speckles.

In a variation of the above described experiment 1% of ultramarine bluepigment may be employed in place of 1% of the Microgrit, so that thespeckles are of a definite blue coloration. In place of the describedproportion of ultramarine blue one may use 0.5 to 2.0% of that pigmentor mixtures of pigment(s) and polishing agent(s) of proportions from1:10 to 10:1 may be used. Alternatively, about 0.1 to 1% of any suitablewater insoluble (or oil soluble) dye may be employed. In such cases thedye solution may be omitted from the dentifrice base formula or may bepresent, providing enough contrast between the speckles and the base isobtainable.

Of course, the various components of the formula may be replaced byothers, such as those previously described, and useful products willalso be obtained. For example, the different mentioned pigments and dyesmay be employed, the sodium lauryl sulfate may be replaced by sodiumethoxylated higher fatty alcohol sulfate or sodium hydrogenated coconutoil fatty acids monoglyceride monosulfate, and the polishing agents maybe replaced by dicalcium phosphate dihydrate and/or dicalcium phosphate(anhydrous) or mixtures thereof. Proportions of the various componentsmay be modified ±10%, ±20%, and ±30%, so long as they are maintainedwithin the ranges previously recited, and the results are satisfactoryproducts of similar properties, although those of the proportions ofthis example are preferred.

EXAMPLE 2 (Actual)

75 Parts of anhydrous dicalcium phosphate and 15 parts of dicalciumphosphate dihydrate, both having average ultimate particle sizes ofabout 4 microns, are mixed with 10 parts of ethyl cellulose and 10 partsof ethyl alcohol in a Hobart mixer. Alternatively, and preferably,ethanol and ethyl cellulose may be premixed and then may be admixed witha previously made blend of the dicalcium phosphates. The mass formed isforced through a screen having uniform openings of 2,000 microns and isthen oven dried for one hour at 65° C. The dried agglomerates are thenscreened through a screen having uniform openings of 420 microns andthose agglomerates which do not pass through a screen having uniformopenings of 177 microns are collected. Next, the agglomerated functionalparticles resulting are mixed with a dentifrice base of the formulagiven in Example 1, with the exception that the polishing agent in suchbase is replaced by sodium aluminosilicate, such as that marketed underthe trade name Zeolite 4A, and the percentage of speckles in the finalproduct is 2% (with the sorbitol solution present being increased by3%).

In variations of this formula there may be substituted for the polishingagent of the speckles, hydrated alumina having an average particle sizeless than about 10 microns, calcium carbonate having particlessubstantially all of which are less than about 7.4 microns in diameter,or insoluble sodium metaphosphate having an average particle size ofabout 5 microns (all such sizes being ultimate particle sizes).

The dentifrices of this example are speckled, transparent or translucentproducts and are aesthetically pleasing in appearance. The visibleparticles of the agglomerated polishing agents (for which otherfunctional insoluble materials may be substituted in whole or in part)are substantially uniformly dispersed in the dentifrice base as visiblyseparate entities and are not substantially impalpable upon use, afterthree months' storage.

EXAMPLE 3 (Actual)

The functional polishing agent constituent of Example 2 is replaced by amixture of ten parts of anhydrous dicalcium phosphate and 90 parts ofcalcium carbonate, with the same total proportion of polishing agentbeing employed; otherwise the same procedure is followed. The productsresulting are similarly satisfactory in functional affects and areaesthetically pleasing in appearance. Similar results are obtained whenthe other disclosed polishing agents are substituted for the presentmixture in the speckles.

EXAMPLE 4 (Theory)

Instead of dissolving the ethyl cellulose in the ethanol or othersuitable solvent, agglomerates are made by blending the polishing agentand ethyl cellulose, sometimes with a reduced proportion of ethanolpresent, to form a powder blend. Such blend is compressed in a rotarytablet press to form slugs, about 6 mm. thick and 25 mm. in diameter.The slugs are then granulated in an oscillating granulator to formsmaller particles, preferably such as will pass through a No. 30 screenand rest on a No. 60 or No. 80 screen. This technique for making thespeckles may also be applied to any of the speckle formulas given in thepreceding examples. Although the binding effect of the ethyl cellulosemight not be as great, the products of this example are alsosatisfactory for incorporation in dentifrices to contribute theiraesthetic advantages and functional effects. If the binding effect ofthe ethyl cellulose in the foregoing formulas is not sufficient, theproportion thereof present may be increased, sometimes up to 100 or200%, but such increases involve additional expenses and therefore the"wet" method, in which solutions of ethyl cellulose in ethanol or othersuitable solvents are employed, is often preferred.

With respect to all the preceding examples, the manufacturer will takecare to adjust the formulation to obtain the desired type of speckle, ofthe desired solubility or "resistance to solubility" in the dentifrice.This may be accomplished by choosing the particular ethyl cellulose inaccordance with the amount of solubilizing flavoring agent (anddetergent and any other lipophile) present. For example, the mediumethyl cellulose previously mentioned may be employed when largerproportions of flavoring agent are present, with the standard ethylcellulose being used for lesser amounts of the flavoring agent (andother lipophiles). Mixtures of the two and mixtures with ethylcelluloses of other characteristics may be made to obtain intermediateproperties. Also, the nature of the lipophilic portion of the dentifricebody may be adjusted, where possible, so as to increase or decreasesolubilizing effects so that the suspended speckles behave in thedesired manner, resisting early disintegration but becoming impalpablethereafter.

The invention has been described with respect to various illustrationsand embodiments thereof but is not to be limited to these because it isevident that one of skill in the art with the present specificationbefore him would be able to utilize substitutes and equivalents withoutdeparting from the invention.

What is claimed is:
 1. A dentifrice comprising water, humectant, gellingagent, detergent and flavor, all of which are constituents of a gelledvehicle of the dentifrice, and a dental polishing agent, uniformlydistributed throughout the vehicle, and visible functional specklesdistributed through the dentifrice which are agglomerates of a waterinsoluble powdered functional material and water insoluble, ethanolsoluble ethyl cellulose binder.
 2. A dentifrice according to claim 1which is in the form of a transparent or translucent gel, with thespeckles visible therein and in which the speckles comprise from 0.1 to10% of the dentifrice.
 3. A dentifrice according to claim 2 wherein thespeckles are comprised of a major proportion of dental polishing agentand a minor proportion of water insoluble, ethanol soluble ethylcellulose.
 4. A dentifrice according to claim 3 wherein the speckles are0.5 to 5% of the dentifrice and are comprised 75 to 98% of dentalpolishing agent, 2 to 20% of ethyl cellulose and 0 to 5% of coloringagent.
 5. A dentifrice according to claim 4 which comprises 5 to 40% ofglycerol, 5 to 50% of sorbitol, 5 to 30% of water, 0.1 to 5% of gellingagent, 0.5 to 5% of dental detergent, 0.5 to 2% of flavor and 10 to 40%of water insoluble dental polishing agent in a continuous phase, and thespeckles comprise 75 to 98% of a dental polishing agent which is anoxide or a salt selected from the group consisting of dicalciumphosphate, tricalcium phosphate, insoluble sodium metaphosphate,alumina, silica, magnesium carbonate, calcium carbonate, calciumpyrophosphate, bentonite and zirconium silicate, and mixtures thereof, 2to 20% of ethyl cellulose and 0.1 to 1% of water insoluble coloringagent, and the proportion of speckles in the dentifrice is 1 to 3%.
 6. Adentifrice according to claim 5 which comprises 20 to 30% of glycerol,25 to 35% of sorbitol, 0.1 to 1% of gelling agent, 1 to 5% ofpolyethylene glycol, 0.5 to 3% of sodium lauryl sulfate dental detergent0.8 to 1.5% of flavoring agent,, 15 to 30% of a dental polishing agentselected from the group consisting of silicon dioxide and sodiumaluminosilicate, and mixtures thereof, and 10 to 25% of water in acontinuous phase, in which dentifrice the speckles comprise 85 to 97% ofa dental polishing agent selected from the group consisting of anhydrousdicalcium phosphate, dicalcium phosphate dihydrate, zirconium silicateand calcined alumina, 3 to 15% of ethyl cellulose and 0.1 to 1% of waterinsoluble dye, and in which the proportion of speckles in the dentifriceis from 1.5 to 2.5%.
 7. A process for preparing a dentifrice comprisingwater, humectant, gelling agent, detergent and flavor, all of which areconstituents of a dental vehicle of the dentifrice, and a dentalpolishing agent, uniformly distributed throughout the vehicle, andvisible functional speckles distributed through the dentifrice which areagglomerates of a water insoluble powdered functional material and waterinsoluble, ethanol soluble ethyl cellulose binder, which comprisesforming said speckles by moistening the water insoluble powderedfunctional material with a solution of water insoluble ethyl cellulosein a solvent, compacting the moistened powder and converting it toparticulate form, drying the particles and collecting those that passthrough a No. 10 U.S. Sieve Series sieve and are retained on a No. 80sieve, dispersing the speckles in the continuous phase of the dentifriceand deaerating the dentifrice subsequently or concurrently.